Mainsail Reefing Techniques; Reefing by the numbers....

[Oldrig]

Norm:

Thanks for starting this fascinating thread. I'll have to get out my sail measurements and calculator and see if I can put together a similar table for my Cape Dory 25D.

and Swede:

I really like your tip about reefing when there's more than 10 degrees of weather helm. That seems like a good guideline for my boat, which needs to reef at just about 15 kts (when flying the full 130 genny).

I've never looked at this scientifically, always relying on the feel of the boat. But 10 degrees of tiller to weather is pretty close to what seems comfortable.

The danger with relying on "feel," of course, is that if you're tired or lazy, you are willing to put up with more weather helm--meaning you'll be crawling forward in heavier weather than necessary when it's time to reef on the fly.

--Joe

[TJim]

One other thing that is extremely relevant is that reefing the main and reefing the head sail (by rolling up
the foot of the sail) also lowers the center of force on your boat so that you can actually use more of the
power that is available without excessive heel to the point that you increase drag. You do however, loose
some wind speed as you lower your sails, but you can use more of the power that is available. TJ

[Norm]

mea culpa

I think I blundered some math.  hate it when that happens! 

Thanks for correcting!

[okawbow]

Norm:


and Swede:

I really like your tip about reefing when there's more than 10 degrees of weather helm. That seems like a good guideline for my boat, which needs to reef at just about 15 kts (when flying the full 130 genny).

I've never looked at this scientifically, always relying on the feel of the boat. But 10 degrees of tiller to weather is pretty close to what seems comfortable.

The danger with relying on "feel," of course, is that if you're tired or lazy, you are willing to put up with more weather helm--meaning you'll be crawling forward in heavier weather than necessary when it's time to reef on the fly.

--Joe

I've noticed on my Bristol 24 with the full main, and 150 genoa up; I can bury the rail and the steering just gets easier. There is actually less weather helm at that point than with moderate wind. Because of that fact, I usually take too long to begin reefing, and end up overpowered. With a reefed main and 100% jib, she also behaves similarly. When the water gets up to the coaming, I lose so much speed, it's much faster to reduce sail before then.

When racing, I used to carry the 150 genoa and full main to 20 knots and more, but I'm learning that it only slows me down over a certain windspeed and percent of heel. I guess it's different for every boat.

I can see where you might be able to use a formula to predict maximum sail area for a given windspeed. You will still have to determine a baseline for every boat by actual experience.

[cubemonkey]

Hi all,
Just logged back in after way too long!

I'll try to get a file together to post that shows Averisera's analysis. I agree that this is a simplistic approach. As the boat turns off the wind, this reduces the perception of being overpowered. So there are a lot of variables (not including each individual boat's characteristics and sail plan) that influence when to reef.

On our 2-skipper boat, we have different responses to the exact same combination of conditions. I wouldn't call it fear for me, it is more caution or risk aversion. Norm is more willing to push things a bit further. This could be not just due to boat characteristics, but now includes such things a personal strength, agility, and gender.

We have reefed many many times this summer. One good thing about a generally heavy weather summer, is that it becomes Heavy Weather Training 101. We've experienced storm cells (singles and multiples), sudden severe squalls and thunderstorms (somewhat normal in summer for our area), dissipating hurricanes, Northeasters, Northwesters, madcap easterlies. If it can happen, it did.

So when do you reef? The discussion Norm began will certainly help us to quantify what we know by instinct. Reefing early is good. But the decision point doesn't need to be negotiated every time we are out sailing. Quantifying our experience gives us language for communicating, and a basis for making decisions. If I'm down below, and the wind picks up, will I be rested when the decision to reef is made? Or will I be groggy and clumsy? Who will go forward? What is the visibility? How much searoom do we have?

If it's already blowing, there is a good chance that I might not have the strength to get the sail down quickly. Or I won't be able to contain it and tie up the bunt. If Norm goes forward, will I be able to hold the boat steady long enough to complete the task. These factors include variables based on the conditions at the time, and our personal capabilities that will also vary depending on how long we have been out, how cold it is, when was our last meal or cup of tea.

The one instance Norm mentioned of being overpowered coming into Boston Harbor, and then having the wind increase inside instead of drop, put us in a position where I literally could not get the sail under control to tie up the bunt. We didn't have enough room to maneuver safely, and the spots we expected the wind to abate, did not deliver. You can wind up putting your boat and yourselves in situations that could have been avoided, if you have a dialogue for the discussion and a method for evaluation. So this topic is just the beginning, and we are hoping it will deliver us happier sails in all conditions.

-elizabeth

[AdriftAtSea]

Hi Elizabeth-

Look forward to seeing your chart/file. :)

[maxiSwede]

[/quote]

I've noticed on my Bristol 24 with the full main, and 150 genoa up; I can bury the rail and the steering just gets easier. There is actually less weather helm at that point than with moderate wind. Because of that fact, I usually take too long to begin reefing, and end up overpowered. With a reefed main and 100% jib, she also behaves similarly. When the water gets up to the coaming, I lose so much speed, it's much faster to reduce sail before then.

When racing, I used to carry the 150 genoa and full main to 20 knots and more, but I'm learning that it only slows me down over a certain windspeed and percent of heel. I guess it's different for every boat.

I can see where you might be able to use a formula to predict maximum sail area for a given windspeed. You will still have to determine a baseline for every boat by actual experience.
[/quote]

Good point. All boats are different, and quite a few, especially with masthead rigs with a quite small main would react as you tell us. I guess you would benefit from deciding from 'degrees of heelng' rather than 'degrees of tiller to windward' then...

It's trial and error.

BTW I'd like to second Norm's comment about how difficult reefing can be on som boats. Really important!

One tio to make reefing easier, assuming of course that the boat is already fitted with 'slab reefing', is to mark the reef lines and or halyards, so you know how much to tighten without having to rediscover this every time.

On Rode Orm, we have a Seldén mast and boom from the mid-eighties. It's fiited with 2 reefs where the lines are inside the boom. All line-hanling is done at the mast and I don't like the 'spaghetti in the cockpit' and aded friction that comes with leading all lines aft. Just my personal view...

Anyway, we always have the reef lines tied to the main sail, and reefing can be done in less than a minute even dead downwind. If alone, I do it this way; First I release the main sheet a bit and let the boat maintain her course. ( unless close-hauled where it gets simpler if I turn some 20 degrees downwind) At the mast I release the boom downhaul, realease the halyard to the tape mark, attach the reef grommet to the hook at the gooseneck, tighten the reef line and then the halyard. Lastly, I retighten the downhaul and 'crawl' back to the cockpit where the sheet will be adjusted again. The first time yu do this Murphy's law makes it an interesting task, but with some training it's really simple and straight-forward.

[sailorflo]

I feel that there should be lots of practice reefing, There have been alot of times that when I thought about reefing it was too late to do it smoothly.  As with anything if you don't do it alot it is not as easy as one might think! All the charts and Graff's don't mean much compared to the boat weight sails ect,ect ect, The best thing to do is go out and sail practice everything  M.O.P ,reefing, and just basic seamanship as much as possible,_Remember the old saying that if you don't use it you lose it

[cubemonkey]

Ok here is the first of probably several. I put this together, but Norm has not seen it yet. It's based on his calcs of our sail area. The rest is just excel crunching the numbers.

I've uploaded this as a pdf. Cap'n K has offered to take my Word format and try to make it look pretty here.  ;D

-elizabeth
http://www.averisera.com/files/Averisera_reef_matrix.pdf

[AdriftAtSea]

Elizabeth-

Here is the PDF as two PNG files, so people can just see them here.

[cubemonkey]

Hey Adrift,
I corrected the table somewhat. The original factors were wrong formula.

Please download the new copy at the same url.

http://www.averisera.com/files/Averisera_reef_matrix.pdf

Sorry for the confusion  :-[

-e

[cubemonkey]

These are the new ones.

They came out a little small. Hmmm.

Anyway, Main +3 is our full main plus the #3 jib.
We have a #4 jib too, at 77%.
So our combos are Main +3, Main +4, 1 Reef + #3, 1 Reef + #4 or 2 Reefs + #3, 2 Reefs +#4, and last Main with 2 reefs.

For pointing we'd probably keep the bigger jib, and downsize the main. Although, our #4 does a fabulous job and keeps the boat balanced. The #4 and 2 reefs is still very powerful, and keeps us sailing usually at hull speed or better, if the conditions are really wild. I'd like to have a storm jib, and a storm trysail. I think there were conditions this summer, that maybe if they weren't exactly warranted, at least were strong enough to test that combo. So what do I want for Christmas? Norm thinks I want a new lightweight #3, but no, I want bright orange storm sails. Such a girl!

-e

[newt]

This thread explains why the Labor day sail was such a nightmare. We went from reefed sailing a 20 knts to over 50 in less than a minute.  Almost got knocked down before we could get to bare poles. By using your figures, we went up about 10 times the force. Now its starting to make sense. Question- has anybody been knocked down under bare poles?